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Tectonic model explaining divergent contraction directions along the Cascadia subduction margin, Washington

P. A. McCrory
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Abstract

Differential motion across the central Cascadia subduction boundary in Washington results in a complex pattern of folds and faults within the shelf and onshore parts of the accretionary margin. Faults and folds above a coastal, north-northwest–trending thrust system provide evidence of ongoing subduction-related contraction. South of this coastal thrust system many fold axes and thrust faults trend east-northeast, in the direction of convergence. These structures are not consistent with a simple subduction system undergoing northeastward convergence. This deformation, adjacent to the boundary between the subduction complex and the Siletz terrane, may be driven by relative convergence between the northward-translating Siletz terrane and the subduction complex. The regional pattern of modern uplift rates is consistent with ongoing north-south contraction across this boundary and the north-south compressional stress field in the area.

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P. A. McCrory. 1996. Tectonic model explaining divergent contraction directions along the Cascadia subduction margin, Washington. https://doi.org/10.1130/0091-7613(1996)024%3C0929%3Atmedcd%3E2.3.co%3B2

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